System and method for computing coverage set and resource allocation in wireless networks

ABSTRACT

The present disclosure discloses a network device and/or method for computing coverage set and resource allocations in wireless networks. The disclosed network device selects a radio frequency subdomain in a wireless network, and further determines a coverage set for the selected radio frequency subdomain. The coverage set includes a subset of access nodes in the selected radio frequency domain. Moreover, a respective access node in the radio frequency subdomain satisfies one of (a) the respective access node is a member of the coverage set, and (b) the respective access node is covered by at least one member of the coverage set with a signal strength stronger than a predetermined threshold.

FIELD

The present disclosure relates to resource mapping and management forwireless devices. In particular, the present disclosure relates tocomputing coverage set and resource allocation in wireless networks.

BACKGROUND

Wireless digital networks, such as networks operating under the currentInstitute of Electrical and Electronics Engineers (IEEE) 802.11standards, are spreading in their popularity and availability. However,resource allocation and management has become increasingly important toachieve energy efficiency, improve network capacity, and providemulti-level function and priority support.

An effective resource allocation management of wireless networkresources has many advantages. First, effective resource allocationmanagement can facilitate energy savings. Specifically, with adequateinformation provided, a control-plane mechanism may determine the leastnumber of network devices in the wireless network to turn on withoutlosing connectivity by any wireless client devices.

Second, effective resource allocation management can also improveutilization of wireless network capacity. Specifically, thecontrol-plane mechanism may facilitate spatial utilization of wirelesscommunication bands, for example, by reducing interference in thehorizontal plane and maximizing frequency utilization in the verticalplane.

Third, effective resource allocation management further improvesmanagement of multi-functional network devices. Today, many networkdevices on the markets are capable of serving multiple networkfunctionalities based on configurations. For example, an access pointdevice may be configured to act as a network access provider under somecircumstances, and to act as a spectrum monitor under othercircumstances. Information provided by the resource allocation andmanagement system can help the control-plane mechanism to determine howto configure functions of the network devices in a wireless network.

In addition, effective resource allocation management can also improvepriority management of multiple network devices. It allows multiplenetwork devices of the same or similar type to be organized in ahierarchical manner. Thus, some network devices will be given higherpriority in the wireless network than other network devices of the sameor similar type, and be placed at a hierarchical level that correspondsto a higher priority.

Various conventional resource allocation methods exist in wirelessnetworks. A typical resource allocation method assigns, for eachwireless client device, an access point from set A, a channel (pair)from set C, and a transmitter power such that all wireless links betweenthe access point and the wireless client device meet a predeterminedSignal-to-Interference Ratio (SIR) requirements.

Existing channel assignment mechanisms, such as Fixed Channel Allocation(FCA) and Dynamic Channel Allocation (DCA), typically are based onsimple heuristic rules. For example, FCA provides for fixed reuse andassignment of wireless communication channels by sectorization anddirectional antennas. FCA partitions the available spectrum into channelsets. The reuse distance constraint is usually satisfied by assigningthe channel sets to the cells in each cluster as determined by, e.g., agraphical coloring scheme. On the other hand, with DCA, channels aretemporarily assigned for use in cells for the duration of a wirelesscall session according to the current system conditions and user needsrather than relying on a priori information. Furthermore, transmitterpower control schemes can adjust the transmit powers of all wirelessusers such that the SIR of each user meets a predetermined minimumthreshold required for acceptable performance.

Note that, conventional resource allocation methods have manylimitations. For example, conventional resource allocation methods donot provide any ways of computing a minimal coverage set that specifiesor identifies the minimum number of radios that is required for coverageon a given wireless frequency band. Due to the importance of resourceallocation management, it is desirable for an enhanced resourceallocation method that is more effective in improving energy efficiencyand network capacity, and in providing multi-level function and prioritysupports for network devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be best understood by referring to thefollowing description and accompanying drawings that are used toillustrate embodiments of the present disclosure.

FIG. 1 shows an exemplary wireless network environment according toembodiments of the present disclosure.

FIG. 2 shows another exemplary wireless network environment according toembodiments of the present disclosure.

FIG. 3 shows an exemplary diagram illustrating radio frequency subdomainpartitioning according to embodiments of the present disclosure.

FIG. 4A shows an exemplary diagram illustrating computing coverage setaccording to embodiments of the present disclosure.

FIG. 4B shows an exemplary table illustrating computing coverage setaccording to embodiments of the present disclosure.

FIGS. 5A-5B show three-dimensional exemplary diagrams illustratingcoverage set according to embodiments of the present disclosure.

FIG. 6 shows a table illustrating channel assignments according toembodiments of the present disclosure.

FIG. 7A shows a line chart illustrating wireless network performancewith average and median co-channel interference (CCI) according toembodiments of the present disclosure.

FIG. 7B shows a line chart illustrating wireless network performancewith non-valid interference at each network device according toembodiments of the present disclosure.

FIG. 7C shows a line chart illustrating average transmit power bynetwork devices according embodiments of the present disclosure.

FIG. 8 is a flowchart illustrating calculation of coverage set forwireless networks according to embodiments of the present disclosure.

FIG. 9 is a flowchart illustrating radio frequency subdomainpartitioning process according to embodiments of the present disclosure.

FIG. 10 is a flowchart illustrating channel assignment process accordingto embodiments of the present disclosure.

FIG. 11 is a block diagram illustrating a system for computing coverageset and resource allocation in wireless networks according toembodiments of the present disclosure.

DETAILED DESCRIPTION

In the following description, several specific details are presented toprovide a thorough understanding. While the context of the disclosure isdirected to resource allocation management in wireless local areanetwork, one skilled in the relevant art will recognize, however, thatthe concepts and techniques disclosed herein can be practiced withoutone or more of the specific details, or in combination with othercomponents, etc. In other instances, well-known implementations oroperations are not shown or described in details to avoid obscuringaspects of various examples disclosed herein. It should be understoodthat this disclosure covers all modifications, equivalents, andalternatives falling within the spirit and scope of the presentdisclosure.

Overview

Embodiments of the present disclosure relate to resource mapping,allocation, and management for wireless devices in general, andcomputing coverage set for resource allocation in wireless local areanetworks (WLAN) in particular. More specifically, techniques for radioresource management in WLAN infrastructure deployments as described inthe present disclosure involve partitioning of the wireless networks,calculating the set required for coverage, performing channel and powerallocations to all network devices (e.g., access points) in the wirelessnetworks. Furthermore, such resource allocations can be adapted todynamically handle interference from both valid network devices (e.g.WLAN devices) and non-valid network devices (e.g. non-WLAN devices).

A centralized approach is described herein to address the issue ofstability and convergence of power and channel allocations, as well asutilizing system-wide information while performing the power and channelallocations. Therefore, the disclosed techniques in the instantapplication will mitigate the lack of steady state, which is a problemobserved with distributed decision making based on local observations.Furthermore, this approach relies on distributed sensing on the networkdevices (such as access points), and centrally collects the path lossgraph and channel properties from the network devices. Because the pathloss graph is relatively invariant, as long as channel properties remainrelatively static, for example, where there is no non-WLAN interference,radar detection, or presence of WLAN interference, the allocations willremain reasonably stable.

Computations are done centrally by a control-plane mechanism on a radiofrequency master device. The radio frequency master device can be anynetwork devices, such as an access point or a network controller.Moreover, the radio frequency master device receives radio frequencyneighbor updates from the network devices (such as access points) in thewireless network. The control-plane mechanism could reside as a process,for example, on a network controller or a server running on the wirelessnetwork. The radio frequency master device comes up with an anchorchannel for each network device (e.g., access point) in the wirelessnetwork. Adjustments to the anchor channel can be made on the networkdevice only on predetermined types of events, such as radar detection,or presence of a non-WLAN interference that degrades the channelquality.

FIG. 1 shows an exemplary wireless network environment according toembodiments of the present disclosure. The wireless network environmentillustrated in FIG. 1 includes network device 110 and a plurality ofother network devices, such as access point 120, access point 125,access point 132, access point 134, and access point 136. Note that, acontrol-plane mechanism runs a process on network device 110. Thecontrol-plane mechanism is capable of computing coverage sets andresource allocations for wireless networks.

In this example, a number of wireless client devices are connected tothe wireless networks through the access points. Specifically, wirelessclient device 150 is connected to access point 120 through a wirelessradio link, and wireless client device 155 is connected to access point125 through another wireless radio link. According to the presentdisclosure, the control-plane mechanism on network device 110 will beable to determine a coverage set that includes only access point 120 andaccess point 125. Thus, network device 110 may instruct other networkdevices, such as access point 132, access point 134, and access point136, to power down without causing any loss of connectivity by anywireless network devices (e.g., wireless network device 150 and wirelessnetwork device 155) in the wireless network.

In order to accomplish the effective resource allocation managementdescribed above, the control-plane mechanism described in the presentdisclosure performs at least four main operations. The first operationpartitions a wireless local area network into radio frequencysubdomains; the second operation computes coverage set of networkdevices required for coverage; the third operation provides channelassignment based on knowledge of path loss and channel characteristicsaround the network device; and, the fourth operation provides transmitpower allocations given the corresponding channel allocations andcoverage set calculation.

Radio Frequency Subdomains

FIG. 2 shows another exemplary wireless network environment according toembodiments of the present disclosure. The wireless network environmentillustrated in FIG. 2 includes network device 220, which is connectedvia wired network connections to a number of other network devices, suchas network device 210 and network device 215. Network devices, such asnetwork device 210, network device 215, and network device 220 caninclude a control-plane mechanism for resource allocation andmanagement. Moreover, these network devices may be organized inhierarchical levels. For example, network device 220 may be configuredas a master controller that communicates with a number of lower levelcontrollers, such as network device 210 and network device 215.

Furthermore, each network device may be connected to a number ofwireless network devices, such as access points, network routers, etc.In this example, network device 210 is connected to access point 240,access point 242, access point 244, and access point 246; and, networkdevice 215 is further connected to access point 232, access point 234,and access point 236. In addition, a physical barrier 250 that iscapable of partially or fully blocking wireless signals also exists inthe depicted wireless network environment. Because of the existence ofphysical barrier 250, wireless communications between certain networkdevices in the wireless network may drop below a desired minimum signallevel.

A radio frequency subdomain typically refers to a subset of networkdevices, any two network devices within which can receive beacon framesfrom other network devices in the subset at signal level above apredetermined threshold. In order to partition the network devicesillustrated in FIG. 2, the control-plane mechanism at the radiofrequency (RF) master device first selects an access point terminated onthat RF master device. In some embodiments, the access point can beselected randomly. In some embodiments, the access point can be selectedaccording to a configuration or profile provided by a networkadministrator.

For illustration purposes only, assuming that network device 210 is a RFmaster device and that network device 210 initially selects access point240. Next, network device 210 checks the network neighborhood that iswithin a certain distance of access point 240, e.g., one hopneighborhood of access point 240, and includes all neighbor nodes fromwhich access point 240 maintains a RF distance within a predeterminethreshold value. In some embodiments, the RF master device may includeall neighbor nodes from which access point 240 can receive wirelesssignals at a signal strength level above a predetermined thresholdvalue. The RF master device marks the starting access point (i.e.,access point 240 in this example) as the root node. Also, for everyneighbor node that satisfies the above criteria, the RF master devicemarks the neighbor node as having been visited.

Furthermore, for each one hop neighbor of access point 240 such asaccess point 242, the RF master device checks the one hop neighborhoodof that one hop neighbor (e.g., access point 242), and includes allneighbor nodes from which access point 242 maintains a RF distancewithin a predetermine threshold value. In some embodiments, the RFmaster device may include all neighbor nodes from which access point 242can receive wireless signals at a signal strength level above apredetermined threshold value. In some embodiments, instead ofdetermining RF neighbors based on RF distances, the RF master device maydetermine RF neighbors based on pass loss values. Note that, the pathloss value may be refined if another neighbor node has a shorter path tothe access point (e.g., access point 242). For every neighbor node ofaccess point 242 that satisfies the above criteria, the RF master devicemarks the neighbor node as having been visited.

Similarly, the RF master device continues the breath-first lookup of itsneighbor nodes until all leaf nodes are within the predetermined RFdistance from the root node, i.e., access point 240 in this example.Accordingly, all nodes in the constructed tree rooted at the root node(e.g., access point 240) form a distinct RF subdomain.

Next, the RF master device selects another node (e.g., access point 246)that is not marked as having been visited. If all nodes are marked ashaving been visited, then the RF subdomain partitioning process iscomplete. Otherwise, the RF master device marks the selected other node(e.g., access point 246) as the root node, and repeats theaforementioned steps to form another distinct RF subdomain. Note that,the RF master device can repeat the root selection and RF subdomainformation process described above until all nodes are marked as havingbeen visited. Therefore, at the end of this process, all access pointsin this example will be partitioned into one or more RF subdomains basedon the path loss graph constructed above.

FIG. 3 shows another example illustrating radio frequency subdomainpartitioning. In FIG. 3, seven access points, including access point310, access point 320, access point 330, access point 340, access point350, access point 370, and access point 380, are partitioned into two RFsubdomains, namely RF subdomain A 300 and RF subdomain B 360. In thisexample, the RF master device (not shown) begins the process at arandomly selected access point in the network (e.g., access point 310),and perform a breadth-first lookup in its one hop neighborhood toidentify all access points that are within a predetermined RF distanceto the selected access point, and add those access points to RFsubdomain A 300. Thus, in this example, access point 310, access point320, access point 330, access point 340, and access point 350 are addedto RF subdomain A 300. Note that, access point 370 and access point 380has a larger RF distance (e.g., as measured by path loss values) thanthe predetermined threshold. Therefore, access point 370 and accesspoint 380 are not included in RF subdomain A 300. Rather, the RF masterdevice selects, e.g., access point 370, as the root node, and repeat theRF subdomain formation process to form RF subdomain B 360. RF subdomainB 360 includes access point 370 and access point 380, where the RFdistance between the two nodes is within the predetermined threshold.

Minimal Coverage Sets

A minimal coverage set generally refers to a minimum number of radios ona given band that are typically required to provide wireless coveragefor a wireless network. Calculation of the minimal coverage set can beperformed based on the following information:

(1) The RF distance or path loss information between different accesspoints in a RF subdomain. Path loss (also referred to as pathattenuation) generally refers to the reduction in power density orattenuation of an electromagnetic wave as the electromagnetic wavepropagates through an airspace. Path loss may be due to many effects,such as free-space loss, refraction, diffraction, reflection,aperture-medium coupling loss, and absorption. Further, path loss isalso influenced by terrain contours, environment (e.g., urban or rural,vegetation and foliage), propagation medium (e.g., dry or moist air),the distance between the transmitter and the receiver, the height andlocation of radio antennas, etc.

(2) The initial transmit power for every network device (e.g., accesspoints) in the RF subdomain. Increasing transmit power on a wirelesscommunication link has numerous benefits. For example, for anyparticular set of channel conditions, a higher transmit power typicallyinfers a higher signal power at the receiver. Having a highersignal-to-noise ratio (SNR) at the receiver consequently reduces the biterror rate of the wireless communication link. In addition, a higher SNRcan also allow a system that uses link adaptation to transmit at ahigher data rate, and thus providing the system with greater spectralefficiency. Moreover, in a wireless fading channel, using highertransmit power provides more protection against a signal fade, and thusreducing probability of dropped calls.

On the other hand, using a higher transmit power, however, has certaindrawbacks as well. For example, overall power consumption in thetransmitting device can be higher due to a high transmit power, whichmay result in reduced battery life in mobile client devicescorrespondingly. Further, interference to other users in the samefrequency band is increased. In some wireless networks where users sharea single frequency and are only separated by different spreading codes,the number of users that can be supported by the network is typicallylimited by the amount of interference presented.

Hence, the initial transmit power selection shall aim at striking abalance between the benefits and drawbacks associated with targeting aparticular transmit power based on the performance criteria andpreference of network administrator.

(3) The available number of orthogonal channels or maximum number ofacceptable neighbors for any network device in the RF subdomain.Orthogonal channels generally are formed when a signal is run through aphase-shifter that shifts the phase by 90 degrees, because the originalsignal and the 90-degree shifted signal are orthogonal to each other.When, for example, orthogonal frequency-division multiplexing (OFDM) isused to encode data on multiple carrier frequencies, the data is dividedinto several parallel data streams or channels, one for each sub-carrierthat is modulated with a conventional modulation scheme, such as, aquadrature amplitude modulation or phase-shift keying at a low symbolrate. Thus, improved utilization of orthogonal channels increases thecapacity or the wireless network.

(4) The minimum desired coverage at every network device (such as accesspoint) assuming the network device is the receiver. In some embodiments,the minimum desired coverage may be configured by the networkadministrator. For example, in a typical enterprise WLAN deploymentscenario, it is preferred that three or more access points will detectand report the received signal strength (RSSI) of any wireless clientdevice in the wireless network. Also, the network administrator mayconfigure that the detected signal strength level from the wirelessclient device shall be −75 dBm or better.

FIG. 4A and FIG. 4B illustrate an example of coverage set computation.For illustration purposes only, FIG. 4A includes RF subdomain A 400.Furthermore, assuming that there are five access points (e.g., accesspoint 410, access point 420, access point 430, access point 440, andaccess point 450) in RF subdomain A 400. FIG. 4B includes a tableshowing the path loss matrix, which includes path loss values betweenany two access points within RF subdomain A 400.

In some embodiments, the coverage set can be represented by a minimumconnected graph corresponding to the selected radio frequency subdomain.In order to compute the coverage set for a RF subdomain, the RF masterdevice perform the following steps:

First, the RF master device computes the maximum transmit power at theaccess points that will result in a minimal coverage set that can berepresented by a minimum connected graph corresponding to the selectedradio frequency subdomain. In some embodiments, the RF master device canalternatively computes a minimum transmit power such that the averagenumber of neighbors for every access point to be as close as possible tothe number of available channels or desired neighbors.

Second, using the transmit power calculated above, the RF master devicedetermines redundant neighbor nodes of every access point, such that theaccess point has coverage from at least a predetermined number ofneighbor nodes (e.g., X nodes) at a pre-determined signal strengththreshold (e.g., 110 dB SNR). Alternatively, overlap can also bedetermined by checking the beacon reports received from wireless clientdevices, or virtual beacon reports collected by multiple access pointsin the network. For example, if two access points both detect a certainnumber or percentage of common wireless client stations in theirvicinity, then the two access points overlap with each other. If suchcondition is met, the RF master device marks the access point asredundant, and determines the coverage set by excluding the redundantnodes from the set of nodes in the RF domain.

In other words, after a coverage set is identified for a RF subdomain,each node in the RF subdomain is either (a) in the coverage area ofanother member node, within which the signal strength received from theother node is above a predetermined threshold value (i.e., a redundantnode), or (b) covers one or more other nodes with signal strength levelbeyond the predetermined threshold value (i.e., a member node within thecoverage set).

In the example illustrated in FIG. 4A, the RF master device may markaccess point 410 and access point 430 as redundant. Therefore, theremaining access points, which include access point 420, access point440, and access point 450, form a coverage set for RF subdomain A 400.Note that, access point 410 and access point 430 are within the coveragearea of access point 420, which due to physical proximity covers bothaccess points with a signal strength level beyond the predeterminethreshold value.

Eventually, the coverage set that includes all of the non-redundantnodes is determined for that RF subdomain. The above steps are repeatedfor all RF subdomains. Therefore, a coverage set will be determined foreach RF subdomain.

In one embodiment, as an example of an extreme case, in order to disablethe coverage set selection, a network administrator could configure thenumber of neighbors (or the available number of channels) to be equal tothe number of nodes in the RF subdomain.

In another embodiment, as another special case, the networkadministrator may configure the number of neighbors to be only one.Therefore, the coverage set computation described above will solve theproblem of calculating coverage set such that there will be at least oneaccess point covering any point.

FIG. 5A and FIG. 5B further describe coverage sets withthree-dimensional diagrams. Specifically, FIG. 5A illustrates the numberof access points that are turned on with maximum transmit power settingsaccording to the technique described in the present disclosure. In FIG.5A, the x-axis 530 indicates the minimum received power between accesspoints; the y-axis 520 indicates the number of orthogonal channels; and,the z-axis 510 indicates the number of access points that have beenturned on.

By contrast, FIG. 5B illustrates the number of access points that areturned on with minimum transmit power settings according to thetechnique described in the present disclosure. In FIG. 5B, the x-axis560 indicates the minimum received power between access points; they-axis 550 indicates the number of orthogonal channels; and, the z-axis540 indicates the number of access points that have been turned on.

For ease of illustration, in the FIG. 5A and FIG. 5B, the minimumreceived power between access points (e.g., x-axis unit) is not taggedwith actual parameters, but a loop counter whose value ranges from 1-35.A value of 1 may indicate, for example, a minimum received power of −50dBm between two access point (or any value up to −80 dBm). Hence, inorder to have −50 dBm coverage at the neighbors, more access points inthe RF subdomain would need to be turned on.

As shown in FIG. 5A, when the transmit power across APs is set to themaximum level, the minimal coverage set computation according toembodiments of the present disclosure results in fewer number of accesspoints remaining ON. At the other extreme, as shown in FIG. 5B, when theminimal coverage set is computed using minimum transmit power, thecomputation described herein would cause more access points to be turnedon.

In this case, since transmit powers are low, the deployment can benefitfrom channel reuse. However, if the initial transmit powers are too low,the low transmit powers may result in coverage holes. The coverage setcomputation in the present disclosure can take this into account of suchfactors. In particular, the RF master device can select a transmit powerthat will satisfy coverage requirements, and meanwhile ensure that themaximum number of access points can remain to be on within the approvedinterference limits.

Note that, the resulting coverage set may be specific to each network.For example, the signal strength levels (such as, signal noise ratio orSNR) criteria may vary from one network to another. If a high signalstrength level is preferred, the coverage set will likely include morenetwork devices. Likewise, if more frequencies or network capacities arepreferred, the coverage set will also include more network devices thatwill be turned on.

Channel Assignments

FIG. 6 shows a table 600 illustrating channel assignments according toembodiments of the present disclosure. The channel assignment mechanismtypically is performed based on a path loss matrix, such as the pathloss matrix illustrated in FIG. 5B.

According to embodiments of the present disclosure, the centralallocation will anchor channel assignment for each access point in theRF subdomain. Particularly, when the access points initially powers up,the access points will use the anchor channel assigned by the RF masterdevice. In some embodiments, local adjustments can be made by the accesspoint based on temporal properties of the channel, such as response toradar detection, presence of a non-WLAN device on that channel with ahigh duty cycle, etc. Moreover, the access points can temporarily applycorrective action to move to another channel while monitoring for theexpiration of the interfering event, and can return back to the anchorchannel selected by the central assignment after the expiration of theevent.

In order to calculate the anchor channel assignment, the RF masterdevice selects a RF subdomain, and further selects a random access pointfrom the minimum coverage set. In some embodiments, priority for channelassignment is given to a subset of essential access points. Accordingly,other access points in the RF subdomain will adjust around the channelassignments to the essential access points.

Several approaches can be used to assign channels. For example,according to a heuristic approach, the RF master device performs thefollowing process:

For each access point AP_(i), where iε{1 . . . n}, and where n equals tothe number of access points within the computed minimal coverage set forthe selected RF subdomain, the RF master device calculates a qualityindex best_quality_(i). The quality index is initialized as INT_MIN.

Next, for each channel Ckε{1 . . . m}, where m equals to the number of20 MHz channels, the RF master device calculates non-valid WLAN networkdevice interference on channel Ck from non-valid network devices. Then,the RF master device calculates valid WLAN network device interferenceon channel Ck from valid network devices. Also, the RF master devicecalculates non-WLAN interference. Finally, the RF master devicecalculates the total quality of channel Ck based on the calculatednon-valid WLAN interference, valid WLAN interference, and non-WLANinterference levels.

If the RF master device determines that the total quality is greaterthan best_quality_(i), then the RF master device will assign the accesspoint to channel Ck. The RF master device then repeats this channelassignment process until all access points in the RF subdomain arevisited.

As an example, table 600 includes two possible resulting channelassignment schemes. Both channel assignment schemes assume that there isno non-WLAN interference, and that there is no non-valid interference(e.g., WLAN interference source from a different network).

The first channel assignment scheme 610 is based on the assumption thatthere are a total of 7 available channels (i.e., channel 36, channel 40,channel 44, channel 48, channel 149, channel 153, and channel 157). Itis further assumed that the adjacent channel overlap weight is 0%.According to the first channel assignment scheme, AP1 620 is assignedchannel 36, AP2 630 is assigned channel 40. AP3 640 is assigned channel48, AP4 650 is assigned channel 153. AP5 660 is assigned channel 44, AP6670 is assigned channel 149, and AP7 680 is assigned channel 157.

The second channel assignment scheme 615 is based on the assumption thatthere are a total of 4 available channels (i.e., channel 36, channel 40,channel 44, and channel 48). It is further assumed that the adjacentchannel overlap weight is 50%. According to the first channel assignmentscheme, AP1 620 is assigned channel 40, AP2 630 is assigned channel 36,AP3 640 is assigned channel 44, AP4 650 is assigned channel 48, AP5 660is assigned channel 40, AP6 670 is assigned channel 48, and AP7 680 isassigned channel 44.

Furthermore, according to embodiments of the present disclosure,

Valid  interference = co-channel  valid  interference + adjacent  channel  valid  interference = Σ(PL_(c) + PL_(a))Non-valid  interference = co-channel  non-valid  interference + adjacent  channel  non-valid  interference = 1/w^(*)Σ(PL_(c) + PL_(a))

where, w=valid to non-valid access point weight; PL_(c)=path loss to anon-valid access point on the same channel; PL_(a)=path loss to anon-valid access point on an adjacent channel such that PL_(c)<X dB,PL_(a)<X dB, and quality a=(1/interference), where X is thepredetermined threshold.

Furthermore, in order to characterize a channel assignment, thefollowing metric can be used:

(1) Given the channel assignment mechanism described above, calculatethe number of co-channel access points for every channel;

(2) Compute the closest distance between access points for that channelassuming that multiple co-channel access points communicate on thechannel; and

(3) Use the closest distance across channels as the qualitative metricto characterize the channel assignment.

Note that, this channel assignment mechanism can be repeated overmultiple iterations up to a total number of the access points multipliedby the number of channels. Further, the assignment with the maximumco-channel neighbor distance can be used for the topology. Thus, thismetric takes into account the co-channel access point cost for everychannel, and thereby attempting to maximize the path loss betweenco-channel access points.

Power Control

Multiple approaches can be adopted to address power allocation problemin accordance with the present disclosure. Specifically, one approachattempts to solve a linear optimization problem. Thus, the RF masterdevice looks for a solution set, such that the interference contributedto each access point by its neighbors is less than the transmit power ofthat access point by a desired margin (SINR). This condition is to befulfilled across all access points in the wireless network. Hence, anaccess point that has more neighbors and is located close to manyneighbors will likely have low transmit power, because a high transmitpower in such circumstances will likely contribute to moreinterferences.

Another approach is rather heuristic, and attempts to achieve a goal,e.g., an access point that has more neighbors and is located close tomany neighbors should be allowed a low transmit power, without the needto solve any linear optimization problem. This approach simplifies thelogic of control-plane mechanism, and avoids the need to deal withnon-feasible solutions, if any. This heuristic approach computes themaximum allowable transmit powers at each of the access points in theminimal coverage set based on the maximum allowed co-channelinterference (CCI) and the density of that access point deployment.Therefore, if the deployment has many close neighbors near an accesspoint, the transmit power of the access point will be lesser than otheraccess points in the RF subdomain.

A. Linear Optimization Approach

Initial transmit power calculation performed as a part of the minimalcoverage set calculation should suffice as a setting for mostdeployments where the distance between access points are similar. Thatis, the entries in the path loss matrix as illustrated in FIG. 5B arewithin 10 dB of the average path loss values.

However, explicit calculation of transmit power and clear channelassessment (CCA) vectors may be essential when the following situationsoccur:

First, transmit power shall be explicitly calculated when the deploymenthas a widely varying path loss matrix. In terms of RF distance, thisimplies that some nodes in the RF subdomain are clustered, while othernodes are spread out within the RF subdomain; or

Second, transmit power needs to be explicitly calculated when the numberof neighbors or assumed number of available channels provided as aninput for minimal coverage set computation is greater than the number ofchannels that are actually available. This could be accomplished byhaving more access points turned on, which implies a higher node degreein the path loss graph. Thus, the deployment will be associated with ahigher spatial re-use. Accordingly, the transmit powers will need to beexplicitly based on channel coloring and RF distances.

In some embodiments, after channel assignments, the power settings andclear channel assessment calculations can be done on a per access point(per-AP) basis. The following parameters will be used for formalization:

-   -   The transmit power of an access point within a subdomain is        denoted as T_(i);    -   Path loss from co-channel AP_(i) to AP_(j) is denoted as        PL_(i,j);    -   CCA threshold selected at AP_(i) is denoted by CCA_(i) (note        that, this value can be ignored from the calculations if        desired);    -   The interference in terms of received power from every non-valid        WLAN devices on the same channel is denoted by R_(k).

For every orthogonal channel, the control-plane mechanism on the RFmaster device solves a linear program, and minimizes the sum of transmitpowers across all access points in the RF subdomain, while ensuring thatthe following constraint is met:

Σ_(i) T _(i)−((Σ_(j) T _(j) PL _(j,i))+Σ_(k) R _(k))−CCA _(i))

The above constraint ensures that some minimum signal-to-interferenceratio (SIR) is made available at every access point. Such a calculationof power setting is especially useful when the RF distance betweenaccess points in a RF subdomain are not homogeneous.

B. Heuristic Approach

Under the heuristic approach, the control-plane mechanism determines anode's average RF distance from its neighbors, and uses this informationto compute transmit power across all access points. Note that, thisheuristic approach does not compute the minimum transmit power vectors.Rather, it computes the maximum allowable transmit powers at each of theaccess points based on the maximum allowed co-channel interference(CCI).

Specifically, the heuristic approach performs the followings:

(1) For every access point from the n access points in the RF subdomain,the control-plane mechanism determines the average RF distance of theaccess point from all other access points.

(2) The control-plane mechanism calculates the transmit power of AP_(i)as the ratio of CCI/(deg(i)*(−avg_pathloss_(i))). The deg(i) functionwill return the number of nodes with a path loss value that is lesserthan a threshold PL_(max). This value can be calculated as the minimumRF distance, at which the maximum transmit power from a neighbor cannotbe heard above a threshold SIR_(threshold). Thus,PL_(max)>=(T_(max)−SIR_(threshold)). For example, if the maximumtransmit power is 20 dBm and the SIR_(threshold) is −70 dB, then theminimum distance for the access point to not be accounted for as aneighbor would be 90 dB. To simplify calculations, the deg(i) functioncan be replaced by (n−1), where n is the number of access points in theRF subdomain.

(3) To enforce a strict limit on the transmit power, instead of usingthe average path loss values, the control-plane mechanism can use theminimum path loss and scale transmit power with that value.

(4) To ensure a minimum level of coverage, the output transmit powerscould also be configured as the element-wise maximum of (a) the minimalcoverage set calculations and (b) the transmit powers computed in (2)above.

To account for interference from non-valid access points and to ensurethat valid access points are not unduly clobbered by interference fromother access points that are not in the RF subdomain, some measures canbe taken to limit the effect that an outside interference source canhave on the transmit powers of valid access points. For example, thetransmit power of AP_(i) calculated in (2) above may be altered as:

(CCI−min(N _(int)(i),L))/(deg(i)*(−avg_pathloss_(i)))

In this equation, L denotes the maximum amount of outside interferencethat our algorithm will accept, and N_(int)(i) indicates the averageinterference seen at the neighbors of AP i, which is calculated as:

k=deg(i)

N _(int)(i)=Σ_(k) R _(k) /k

In this equation, Σ_(k)R_(k) denotes the total received interferencefrom non-valid access points at all of AP_(i)'s k neighbors.

C. Activation and Frequency Control

The activation of the above-mentioned radio management can be atdifferent time scales as justified by either a coarse grained resourcecontrol or a fine grained resource control.

With a coarse grained resource control, the default granularity is toexecute the mechanism in the order of hours. The other factorcontrolling the frequency of the coarse grained activation is the amountof co-channel interference (CCI) experienced by each access point. Ifthe CCI is beyond a pre-determined threshold, and a timer set for coarsegrained control has elapsed, the minimal coverage set computation andchannel assignment mechanisms will be run on the RF subdomain. Notethat, running these two schemes on a coarser time scale ensures that thesystem is stable. It also ensures that wireless client devices do notget regularly de-authenticated due to shut-down activities of accesspoints, or due to change of allocated channels.

By contrast, with fine grained resource control, the power allocationmechanism is executed on a finer time scale. This mechanism is allowedto be performed more frequently than the channel assignment and minimalcoverage set calculation mechanisms, because it will not cause awidespread disruption of service. Like the coarse grained resourcecontrol, the power allocation re-calculation is done when the fine timescale timer expires, and the interference seen at the access pointsexceeds a pre-determined tolerable interference threshold levels.

The timer intervals, tolerable interference thresholds, and thethreshold for the maximum number of associated users are configurableand dependent upon the stability desired from the system.

In some embodiments, the power control mechanism uses a path loss matrixwith the additional constraint that all access points in the RFsubdomain have been assigned a single channel. Specifically, the powercontrol mechanism calculates the minimum transmit powers across allaccess points as a vector, e.g. (11, 11, 12, 11, 11, 11, 11) dBm. Thisvector corroborates with observations from the path loss matrix, inwhich the RF distances do not vary much. In this example, a minimumdesired SIR of −50 dB is selected.

It is important to note that using an optimization solver can sometimesresult in infeasible solutions. Hence, in some embodiments, a simpleheuristic approach is preferred. With the heuristic approach, unlike theoptimization problem which solves for the minimum transmit power vector,the power control mechanism computes the maximum allowable transmitpower vector that matches the SIR constraints.

FIG. 7A shows a line chart illustrating wireless network performancewith average and median co-channel interference (CCI) according toembodiments of the present disclosure. In this example, the maximumtolerable CCI at every access point is varied from −70 to −40 dB asplotted by the x-axis of FIG. 7A. The y-axis of FIG. 7A plots thedifference in the desired CCI and the average and median CCI observedacross all access points. For most scenarios, the illustrated powercontrol mechanism performs well and the difference between the observedand tolerated CCI is within 4 dB. However, as the maximum tolerable CCIincreases towards the right end of the x-axis, the differences betweenthe desired CCI and observed CCI are greater than what can be tolerated.This is because the transmit power is limited at 20 dBm while thetolerated CCI increases, and thus the power control mechanism results ina much lower level of CCI.

Next, considering the impact of external interference on the performanceof the transmit power control mechanism according to the presentdisclosure. In this case, we assume that the sum of externalinterference at all access points is −65 dBm. However, the power controlmechanism can limit the amount of outside interference to be, forexample, 3 dB less than the aggregate CCI that the access points in theRF subdomain can tolerate. This is done to ensure that the outsideinterference does not make valid access point's transmit powers decreasedramatically, which in turn results in deterioration of wireless networkperformance. Furthermore, in some embodiments, the limit allowed on theamount of outside interference may be adjustable or configurable by anetwork administrator.

Simulation results of the above study are as shown in FIG. 7B and FIG.7C. Specifically, FIG. 7B shows a line chart illustrating wirelessnetwork performance with non-valid interference at each network deviceaccording to embodiments of the present disclosure. As illustrated inFIG. 7B, even with outside interference, the power control mechanism inaccordance with the present disclosure is able to limit the CCI within 6dB. Note that, for the initial part of the graph, the difference betweenthe desired CCI and observed CCI is high, because the externalinterference dominates even when the lowest transmit powers areselected. Nevertheless, as the allowable CCI increases, the performanceof the power control mechanism described herein improves, and only to belimited by the maximum settable transmit power.

FIG. 7C shows a line chart illustrating average transmit power bynetwork devices according embodiments of the present disclosure. Asillustrated in FIG. 7C, the average transmit powers for the case with nooutside interference and with −65 dBm interference at each access pointincrease monotonically with increasing acceptable values of CCI. Also,note that the mean transmit power in the cases with interference growsslowly as compared to the cases with no outside interference. This helpsto keep the total CCI at the access points within the desired limits.

Process for Computing Coverage Set and Resource Allocations

FIG. 8 shows a flowchart illustrating calculation of coverage set forwireless networks according to embodiments of the present disclosure.During operations, a RF master device first selects a radio frequencysubdomain (operation 800). Then, the RF master device calculates aminimum transmit power at access nodes within the selected RF domain(operation 805). Next, the RF master device recursively adds redundantaccess nodes to generate desired coverage set based on the calculatedminimum transmit power (operation 810). In addition, the RF masterdevice checks whether every access node in the selected RF subdomain iseither active by itself, or in coverage with a signal strength levelabove a predetermined signal level threshold by an active neighboringaccess node (operation 815). If so, the RF master device determines thedesired coverage set based on the previously added redundant accessnodes (operation 820). Note that, the desired coverage set can bederived by removing all previously added redundant access nodes from theRF subdomain. If not every access node in the selected RF subdomainsatisfies the above criteria, the RF master repeats the recursiveprocess and marks additional redundant nodes or active nodes.

FIG. 9 is a flowchart illustrating radio frequency subdomainpartitioning process according to embodiments of the present disclosure.During operations, the RF master device first selects an access node asa root node (operation 910). Next, the RF master device adds to the RFsubdomain all access nodes within a predetermined RF distance to theroot node among the nodes in the one-hop neighborhood of the root node(operation 920). The RF master device then determines whether all leafnodes are within the predetermined RF threshold distance to the rootnode (operation 930). If so, the RF master device identifies next accessnode to visit as a visiting node (operation 940). Furthermore, the RFmaster device determines whether each of the one-hop neighbor nodes ofthe visiting node is within the predetermined RF threshold distance tothe root node (operation 950). If a respective one-hop neighbor node ofthe visiting node is within the predetermined RF threshold distance tothe root node, then the RF master device adds to the RF subdomain therespective one-hop neighbor node of the visiting node (operation 960).Also, the RF master device will mark the added on-hop neighbor node as avisited node (operation 970).

If the RF master device determines that not all leaf nodes are withinthe predetermined RF threshold distance to the root node, the RF masterdevice further determines whether all nodes are visited (operation 980).If not, the RF master device identifies an access node that has not beenvisited, selects the identified node as a new root node, and repeats thetree construction process described above during operations 910-970.

Note that, the RF master device recursively checks whether all nodes aremarked as visited (operation 980). If the RF master device determinesthat all nodes have been visited, the RF master device will identify RFsubdomains based on node groups under each root node (operation 990).Specifically, all nodes connected to the same root node in the same treeform a single RF subdomain. Thus, the number of root nodes (or thenumber of constructed trees in the graph) corresponds to the totalnumber of partitioned RF subdomains.

FIG. 10 is a flowchart illustrating channel assignment process accordingto embodiments of the present disclosure. During operations, the RFmaster device first selects a RF subdomain (operation 1010). Then, theRF master device selects each access node from the desired coverage set(e.g., a minimal coverage set) (operation 1020). Also, the RF masterdevice selects a wireless communication channel (operation 1030). Next,the RF master device performs the following calculations without anyspecific orders:

The RF master device calculates the level of non-valid access nodeinterference (e.g., interference caused by a network device from adifferent wireless network) on selected channel from non-valid accessnodes (operation 1040);

The RF master device calculates the level of valid access nodeinterference (e.g., interference caused by a network device from withinthe same wireless network) on selected channel from valid access nodes(operation 1050); and

The RF master device calculates the level of non-wireless local areanetwork (WLAN) interference (e.g., interference caused by a non-wirelessnetwork device such as a microwave machine) (operation 1060).

Subsequently, the RF master device calculates a quality index for achannel assignment scheme based on the calculated non-valid access nodeinterference, valid access node interference, and non-WLAN interference(operation 1070). The RF master device may calculate different qualityindex values for various channel assignment schemes using the abovefactors. Eventually, the RF master device can select from multiplechannel assignment schemes a preferred channel assignment scheme bycomparing the quality index value associated with each channelassignment scheme (operation 1080).

System for Computing Coverage Set and Resource Allocations

FIG. 11 is a block diagram illustrating a system for computing minimalcoverage set and resource allocation in wireless networks according toembodiments of the present disclosure.

Operating as a RF master device, network device 1100 includes at leastone or more radio antennas 1110 capable of either transmitting orreceiving radio signals or both, a network interface 1120 capable ofcommunicating to a wired or wireless network, a processor 1130 capableof processing computing instructions, and a memory 1140 capable ofstoring instructions and data. Moreover, network device 1100 furtherincludes a receiving mechanism 1150, a transmitting mechanism 1160, aradio frequency subdomain partitioning mechanism 1170, a coverage setidentifying mechanism 1180, a channel assigning mechanism 1190, and apower controlling mechanism 1195, all of which are coupled to processor1130 and memory 1140 in network device 1100. Network device 1100 may beused as a client system, or a server system, or may serve both as aclient and a server in a distributed or a cloud computing environment.

Radio antenna 1110 may be any combination of known or conventionalelectrical components for receipt of signaling, including but notlimited to, transistors, capacitors, resistors, multiplexers, wiring,registers, diodes or any other electrical components known or laterbecome known.

Network interface 1120 can be any communication interface, whichincludes but is not limited to, a modem, token ring interface, Ethernetinterface, wireless IEEE 802.11 interface, cellular wireless interface,satellite transmission interface, or any other interface for couplingnetwork devices.

Processor 1130 can include one or more microprocessors and/or networkprocessors. Memory 1140 can include storage components, such as, DynamicRandom Access Memory (DRAM), Static Random Access Memory (SRAM), etc.

Receiving mechanism 1150 receives one or more network messages vianetwork interface 1120 or radio antenna 1110 from a wireless client. Thereceived network messages may include, but are not limited to, requestsand/or responses, beacon frames, management frames, control path frames,and so on. Each message may comprise one or more data packets, forexample, in the form of IP packets. In some embodiments, receivingmechanism 1150 receives both a radio frequency (RF) subdomain and acoverage set corresponding to the received RF subdomain. Note that, thecoverage set include a minimal coverage set that corresponds to aminimum number of radios for providing coverage by the wireless network.

Transmitting mechanism 1160 transmits messages, which include, but arenot limited to, requests and/or responses, beacon frames, managementframes, control path frames, and so on.

Radio frequency subdomain partitioning mechanism 1170, according toembodiments of the present disclosure, partitions a plurality of accessnodes in the wireless network into a plurality of radio frequencysubdomains based on a path loss matrix. The path loss matrix includespath loss values between pairs of the access nodes within the coverageset. Each radio frequency subdomain includes access nodes whose radiofrequency distances to a selected root node are within a predeterminedthreshold.

Specifically, radio frequency subdomain partitioning mechanism 1170selects an access node as a root node, and adds to the RF subdomain allaccess nodes within a predetermined RF distance to the root node amongthe nodes in the one-hop neighborhood of the root node.

Next, radio frequency subdomain partitioning mechanism 1170 determineswhether all leaf nodes are within the predetermined RF thresholddistance to the root node. If so, radio frequency subdomain partitioningmechanism 1170 identifies the next access node to visit as a visitingnode, and further determines whether each of the one-hop neighbor nodesof the visiting node is within the predetermined RF threshold distanceto the root node. If a respective one-hop neighbor node of the visitingnode is within the predetermined RF threshold distance to the root node,then radio frequency subdomain partitioning mechanism 1170 adds to theRF subdomain the respective one-hop neighbor node of the visiting node,and also marks the added on-hop neighbor node as a visited node.

If radio frequency subdomain partitioning mechanism 1170 determines thatnot all leaf nodes are within the predetermined RF threshold distance tothe root node, radio frequency subdomain partitioning mechanism 1170further determines whether all nodes are visited. If not, radiofrequency subdomain partitioning mechanism 1170 identifies an accessnode that has not been visited, selects the identified node as a newroot node, and repeats the tree construction process described above.Note that, radio frequency subdomain partitioning mechanism 1170recursively checks whether all nodes are marked as visited. If all nodeshave been visited, radio frequency subdomain partitioning mechanism 1170will identify RF subdomains based on node groups under each root node.That is, all nodes connected to the same root node in the same tree forma single RF subdomain. Thus, the number of root nodes or the number ofconstructed trees in the graph corresponds to the total number ofpartitioned RF subdomains.

Coverage set identifying mechanism 1180 generally identifies a coverageset for a selected RF subdomain. Specifically, coverage set identifyingmechanism 1180 selects a radio frequency subdomain in a wirelessnetwork, and determines a coverage set for the selected radio frequencysubdomain. The coverage set includes a subset of a plurality of accessnodes in the RF subdomain. Moreover, a respective access node in theplurality of access nodes satisfies either (a) the respective accessnode is a member of the coverage set, or (b) the respective access nodeis covered by at least one member of the coverage set with a signalstrength stronger than the predetermined threshold.

In addition, coverage set identifying mechanism 1180 also calculates aminimum transmit power at the plurality of access nodes in the radiofrequency subdomain, identifies a plurality of redundant access nodes inthe radio frequency subdomain, and determines the coverage set byexcluding the identified redundant access nodes from the plurality ofaccess nodes in the radio frequency subdomain.

In some embodiments, the plurality of redundant access nodes areidentified based on one or more of an initial transmit power, anavailable number of orthogonal channels, a target number of neighbors,and a coverage goal at each access node. In some embodiments, thecoverage goal includes a signal strength threshold level in decibels. Insome embodiments, an average number of neighbors for each access node inthe coverage set is approximate to the available number of orthogonalchannels.

In some embodiments, the coverage set is calculated such that at leastone access node covers each wireless client device in the wirelessnetwork in response to the target number of neighbors being equal toone. In some embodiments, the coverage set includes every access node inthe radio frequency subdomain if the target number of neighbors equalsto the number of the plurality of access nodes in the radio frequencysubdomain.

In some embodiments, coverage set identifying mechanism 1180 alsodetermines whether a respective access node has coverage from at least apredetermined number of neighbors with a signal strength that isstronger than a predetermined signal strength threshold level. In someembodiments, coverage set identifying mechanism 1180 also collectsbeacon reports that are associated with beacon frames. Further, thebeacon reports are received from a plurality of wireless client devicesby a plurality of network devices in the wireless network, anddetermines whether a number of beacon reports that include common accessnodes exceeds a threshold.

Channel assigning mechanism 1190 generally assigns channels to accessnodes in a minimal coverage set. Specifically, channel assigningmechanism 1190 selects either a capacity mode or a coverage mode as anoperating mode of the RF subdomain if a measure of network activitysatisfies a predetermined condition, and further performs radio resourcemanagement in the radio frequency subdomain based on the selectedoperating mode.

The measure of network activity will satisfy a predetermined condition,for example, when: (1) a number of client devices in the radio frequencysubdomain satisfies a threshold condition; (2) a traffic load in theradio frequency subdomain satisfies a threshold condition; (3) a densityof the client devices in the radio frequency subdomain satisfies athreshold condition; (4) a relative location of client devices tonetwork devices in the radio frequency subdomain satisfies a thresholdcondition; (5) a physical movement of client devices in the radiofrequency subdomain satisfies a threshold condition; (6) a time of daybeing within a preconfigured time range; etc.

In addition, performing the radio resource management may involveperforming one of more of: assigning channels to access points in theradio frequency subdomain; assigning transmit power levels to the accesspoints in the radio frequency subdomain; assigning receive sensitivitylevels to the access points in the radio frequency subdomain; selectingbetween power on and power off for the access points in the radiofrequency subdomain; etc.

Furthermore, in some embodiments, if the coverage mode is selected asthe operating mode of the RF subdomain, selecting between power on andpower off for the access points involves selecting power on for theaccess points that are within the minimal coverage set, and selectingpower off for the access points that are in the radio frequencysubdomain but outside the minimal coverage set.

In some embodiments, channel assigning mechanism 1190 determines achannel assigning scheme for access nodes within the minimal coverageset.

Also, channel assigning mechanism 1190 calculates a quality index forthe channel assigning scheme based on a first level of non-valid accessnode interference, a second level of valid access node interference, anda third level of non-wireless local area network interference. Moreover,in some embodiments, channel assigning mechanism 1190 calculates thefirst level of non-valid access node interference on a selected channelfrom non-valid access nodes. In some embodiments, channel assigningmechanism 1190 calculates the second level of valid access nodeinterference on a selected channel from valid access nodes. In someembodiments, channel assigning mechanism 1190 calculates the third levelof non-wireless local area network interference. Furthermore, channelassigning mechanism 1190 assigns channels to the access nodes within theminimal coverage set based on the quality index.

Moreover, in some embodiments, channel assigning mechanism 1190 furthercan switch the operating mode of the radio frequency subdomain fromcoverage mode to capacity mode, and re-assign channels to all accesspoints in the radio frequency subdomain.

Power controlling mechanism 1195 generally assigns transmit power levelsand/or sensitivity levels to the access points within a coverage set.For example, power controlling mechanism 1195 can assign transmit powerlevels to the access points within the minimal coverage set that receivethe same channel assignment and assign sensitivity levels to the accesspoints based on the assigned transmit power levels.

Specifically, power controlling mechanism 1195 selects a transmit powerassociated with a respective access node in the coverage set to obtain acoverage objective. For example, the coverage objective may include aminimum signal strength level and a maximum tolerable interferencelevel.

In some embodiments, power controlling mechanism 1195 receives a pathloss matrix, which includes path loss values between pairs of the accessnodes within the coverage set. Power controlling mechanism 1195 thendetermines the transmit power associated with the respective access nodeusing an initial transmit power if the path loss matrix indicates thatdistances between the pairs of the access nodes are similar. On theother hand, power controlling mechanism 1195 may recalculate thetransmit power associated with the respective access node if the pathloss matrix indicates that distances between the pairs of the accessnodes vary beyond a threshold.

In some embodiments, power controlling mechanism 1195 assigns transmitpower levels based on a maximum allowed co-channel interference (CCI)and a deployment density of access points operating on the same channelin the radio frequency subdomain. In some embodiments, power controllingmechanism 1195 determines whether (a) the first access node has moreneighbors than the second access node, or (b) the first access node islocated closer to neighboring access nodes than the second access node.If either (a) or (b) is true, power controlling mechanism 1195 sets thefirst access node to have lower transmit power than the second accessnode in the coverage set.

Therefore, receiving mechanism 1150, transmitting mechanism 1160, radiofrequency subdomain partitioning mechanism 1170, coverage setidentifying mechanism 1180, channel assigning mechanism 1190, and powercontrolling mechanism 1195 often collectively operate with each other tocompute minimal coverage set and provide resource allocations inwireless networks.

According to embodiments of the present disclosure, network servicesprovided by wireless network device 1100, solely or in combination withother wireless network devices, include, but are not limited to, anInstitute of Electrical and Electronics Engineers (IEEE) 802.1xauthentication to an internal and/or external Remote AuthenticationDial-In User Service (RADIUS) server; an MAC authentication to aninternal and/or external RADIUS server; a built-in Dynamic HostConfiguration Protocol (DHCP) service to assign wireless client devicesIP addresses; an internal secured management interface; Layer-3forwarding; Network Address Translation (NAT) service between thewireless network and a wired network coupled to the network device; aninternal and/or external captive portal; an external management systemfor managing the network devices in the wireless network; etc.

The present disclosure may be realized in hardware, software, or acombination of hardware and software. The present disclosure may berealized in a centralized fashion in one computer system or in adistributed fashion where different elements are spread across severalinterconnected computer systems coupled to a network. A typicalcombination of hardware and software may be an access point with acomputer program that, when being loaded and executed, controls thedevice such that it carries out the methods described herein.

The present disclosure also may be embedded in non-transitory fashion ina computer-readable storage medium (e.g., a programmable circuit; asemiconductor memory such as a volatile memory such as random accessmemory “RAM,” or non-volatile memory such as read-only memory,power-backed RAM, flash memory, phase-change memory or the like; a harddisk drive; an optical disc drive; or any connector for receiving aportable memory device such as a Universal Serial Bus “USB” flashdrive), which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

As used herein, “network device” generally includes a device that isadapted to transmit and/or receive signaling and to process informationwithin such signaling such as a station (e.g., any data processingequipment such as a computer, cellular phone, personal digitalassistant, tablet devices, etc.), an access point, data transfer devices(such as network switches, routers, controllers, etc.) or the like.

As used herein, “access point” (AP) generally refers to receiving pointsfor any known or convenient wireless access technology which may laterbecome known. Specifically, the term AP is not intended to be limited toIEEE 802.11-based APs. APs generally function as an electronic devicethat is adapted to allow wireless devices to connect to a wired networkvia various communications standards. Access points are usedinterchangeably as access nodes in the present disclosure.

As used herein, the term “interconnect” or used descriptively as“interconnected” is generally defined as a communication pathwayestablished over an information-carrying medium. The “interconnect” maybe a wired interconnect, wherein the medium is a physical medium (e.g.,electrical wire, optical fiber, cable, bus traces, etc.), a wirelessinterconnect (e.g., air in combination with wireless signalingtechnology) or a combination of these technologies.

As used herein, “information” is generally defined as data, address,control, management (e.g., statistics) or any combination thereof. Fortransmission, information may be transmitted as a message, namely acollection of bits in a predetermined format. One type of message,namely a wireless message, includes a header and payload data having apredetermined number of bits of information. The wireless message may beplaced in a format as one or more packets, frames or cells.

As used herein, “wireless local area network” (WLAN) generally refers toa communications network links two or more devices using some wirelessdistribution method (for example, spread-spectrum or orthogonalfrequency-division multiplexing radio), and usually providing aconnection through an access point to the Internet; and thus, providingusers with the mobility to move around within a local coverage area andstill stay connected to the network.

As used herein, the term “mechanism” generally refers to a component ofa system or device to serve one or more functions, including but notlimited to, software components, electronic components, electricalcomponents, mechanical components, electro-mechanical components, etc.

As used herein, the term “embodiment” generally refers an embodimentthat serves to illustrate by way of example but not limitation.

It will be appreciated to those skilled in the art that the precedingexamples and embodiments are exemplary and not limiting to the scope ofthe present disclosure. It is intended that all permutations,enhancements, equivalents, and improvements thereto that are apparent tothose skilled in the art upon a reading of the specification and a studyof the drawings are included within the true spirit and scope of thepresent disclosure. It is therefore intended that the following appendedclaims include all such modifications, permutations and equivalents asfall within the true spirit and scope of the present disclosure.

While the present disclosure has been described in terms of variousembodiments, the present disclosure should not be limited to only thoseembodiments described, but can be practiced with modification andalteration within the spirit and scope of the appended claims. Likewise,where a reference to a standard is made in the present disclosure, thereference is generally made to the current version of the standard asapplicable to the disclosed technology area. However, the describedembodiments may be practiced under subsequent development of thestandard within the spirit and scope of the description and appendedclaims. The description is thus to be regarded as illustrative ratherthan limiting.

What is claimed is:
 1. A method comprising: receiving, by a networkdevice, a radio frequency subdomain and a coverage set for the radiofrequency subdomain in a wireless network, wherein the coverage setcomprises a minimal coverage set that corresponds to a minimum number ofradios for providing coverage by the wireless network; selecting one ofa capacity mode and a coverage mode as an operating mode of the radiofrequency subdomain in response to a measure of network activitysatisfying a predetermined condition; and performing radio resourcemanagement in the radio frequency subdomain based on the selectedoperating mode.
 2. The method of claim 1, wherein network activitysatisfying the predetermined condition further comprises one or more of:a number of client devices in the radio frequency subdomain satisfying athreshold condition; a traffic load in the radio frequency subdomainsatisfying a threshold condition; a density of the client devices in theradio frequency subdomain satisfying a threshold condition; a relativelocation of client devices to access nodes in the radio frequencysubdomain satisfying a threshold condition; a physical movement ofclient devices in the radio frequency subdomain satisfying a thresholdcondition; a time of day being within a preconfigured time range; and aclient's capability of communicating on a particular channel.
 3. Themethod of claim 1, wherein performing the radio resource managementcomprises performing one or more of: assigning channels to access nodesin the radio frequency subdomain; assigning transmit power levels to theaccess nodes in the radio frequency subdomain; assigning receivesensitivity levels to the access nodes in the radio frequency subdomain;assigning receive sensitivity levels to the first set of access nodes inthe first radio frequency subdomain; assigning bandwidth of operation tothe first set of access nodes in the first radio frequency subdomain;and selecting between power on and power off for the access nodes in theradio frequency subdomain.
 4. The method of claim 3, wherein selectingbetween power on and power off for the access nodes in the radiofrequency subdomain further comprises: in response to the coverage modebeing selected as the operating mode, selecting power on for accessnodes within the minimal coverage set; and selecting power off foraccess nodes in the radio frequency subdomain but outside the minimalcoverage set.
 5. The method of claim 3, wherein assigning channels toaccess nodes in the radio frequency subdomain further comprises:determining, by the network device, a channel assigning scheme foraccess nodes within the minimal coverage set; calculating, by thenetwork device, a quality index for the channel assigning scheme basedon a first level of non-valid access node interference, a second levelof valid access node interference, and a third level of non-wirelesslocal area network interference; and assigning, by the network device,channels to the access nodes within the minimal coverage set based onthe quality index.
 6. The method of claim 5, further comprises:switching the operating mode of the radio frequency subdomain tocapacity mode; and re-assigning channels to all access nodes in theradio frequency subdomain.
 7. The method of claim 5, wherein calculatingthe quality index further comprises: calculating, by the network device,the first level of non-valid access node interference on a selectedchannel from non-valid access nodes; calculating, by the network device,the second level of valid access node interference on the selectedchannel from valid access nodes; and calculating, by the network device,the third level of non-wireless local area network interference.
 8. Themethod of claim 5, further comprising: assigning transmit power levelsto the access nodes within the minimal coverage set that receive thesame channel assignment.
 9. The method of claim 3, further comprising:selecting, by the network device, a transmit power associated with arespective access node in the coverage set to obtain a coverageobjective, which comprises a minimum signal strength level and a maximumtolerable interference level.
 10. The method of claim 9, furthercomprising: switching the operating mode of the radio frequencysubdomain to capacity mode; and recalculating the transmit power levelassociated with the respective access node.
 11. The method of claim 3,further comprising: assigning transmit power levels based on a maximumallowed co-channel interference (CCI) and a deployment density of accessnodes operating on the same channel in the radio frequency subdomain;and assigning the sensitivity levels based on the assigned transmitpower levels.
 12. A network device comprising: a processor; a memory; areceiving mechanism operating with the processor, the receivingmechanism to receive a radio frequency subdomain and a coverage set forthe radio frequency subdomain in a wireless network, wherein thecoverage set comprises a minimal coverage set that corresponds to aminimum number of radios for providing coverage by the wireless network;and a channel assigning mechanism operating with the processor, thechannel assigning mechanism to: select one of a capacity mode and acoverage mode as an operating mode of the radio frequency subdomain inresponse to a measure of network activity satisfying a predeterminedcondition; and perform radio resource management in the radio frequencysubdomain based on the selected operating mode.
 13. The network deviceof claim 12, wherein network activity satisfying the predeterminedcondition further comprises one or more of: a number of client devicesin the radio frequency subdomain satisfying a threshold condition; atraffic load in the radio frequency subdomain satisfying a thresholdcondition; a density of the client devices in the radio frequencysubdomain satisfying a threshold condition; a relative location ofclient devices to access nodes in the radio frequency subdomainsatisfying a threshold condition; a physical movement of client devicesin the radio frequency subdomain satisfying a threshold condition; atime of day being within a preconfigured time range; and a client'scapability of communicating on a particular channel.
 14. The networkdevice of claim 12, further comprises a power controlling mechanismoperating with the processor, the power controlling mechanism to performone or more of: assign channels to access nodes in the radio frequencysubdomain; assign transmit power levels to the access nodes in the radiofrequency subdomain; assign receive sensitivity levels to the accessnodes in the radio frequency subdomain; assign receive sensitivitylevels to the first set of access nodes in the first radio frequencysubdomain; assign bandwidth of operation to the first set of accessnodes in the first radio frequency subdomain; and select between poweron and power off for the access nodes in the radio frequency subdomain.15. The network device of claim 14, wherein while selecting betweenpower on and power off for the access nodes in the radio frequencysubdomain, the power controlling mechanism: in response to the coveragemode being selected as the operating mode, to select power on for accessnodes within the minimal coverage set; and to select power off foraccess nodes in the radio frequency subdomain but outside the minimalcoverage set.
 16. The network device of claim 14, wherein whileassigning channels to access nodes in the radio frequency subdomain, thechannel assignment mechanism further to: determine a channel assigningscheme for access nodes within the minimal coverage set; calculate aquality index for the channel assigning scheme based on a first level ofnon-valid access node interference, a second level of valid access nodeinterference, and a third level of non-wireless local area networkinterference; and assign channels to the access nodes within the minimalcoverage set based on the quality index.
 17. The network device of claim16, wherein the channel assigning mechanism further to: switch theoperating mode of the radio frequency subdomain to capacity mode; andre-assign channels to all access nodes in the radio frequency subdomain.18. The network device of claim 16, wherein channel assigning mechanismfurther to: calculate the first level of non-valid access nodeinterference on a selected channel from non-valid access nodes;calculate the second level of valid access node interference on aselected channel from valid access nodes; and calculate the third levelof non-wireless local area network interference.
 19. The network deviceof claim 14, wherein the power controlling mechanism further to: assignthe transmit power levels to the access nodes within the minimalcoverage set that receive the same channel assignment; and select atransmit power associated with a respective access node in the coverageset to obtain a coverage objective, which comprises a minimum signalstrength level and a maximum tolerable interference level.
 20. Thenetwork device of claim 19, wherein the power controlling mechanismfurther to assign the transmit power levels based on a maximum allowedco-channel interference (CCI) and a deployment density of access nodesoperating on the same channel in the radio frequency subdomain; andwherein the power controlling mechanism further to assign thesensitivity levels based on the assigned transmit power levels.